Cohort study to measure COVID-19 vaccine effectiveness among health workers in the WHO European Region: guidance document (2021)

This guidance document outlines the methods of a prospective one-year cohort study of hospital-based healthcare workers (HWs) to evaluate the effectiveness of COVID-19 vaccine in preventing laboratory-confirmed SARS-CoV-2 infection.

This document is intended to be used as a guidance document to support countries and institutions that are interested in conducting research on COVID-19 vaccine effectiveness in health workers. It outlines an approach to post-introduction COVID-19 vaccine effectiveness evaluation in HWs that complements existing WHO Unity Studies, which focus on sero-epidemiological investigations. Research should be conducted only after site-specific protocols are developed and approved by the relevant local ethical review committee(s).